DESCRIPTION: (Applicant's Description) The broad, long-term objective of this proposal is to increase our understanding of how adolescent's subjective experience of early trials of cigarette smoking impacts upon their future smoking behavior. The Specific Aims are 1) to increase our understanding of the subjective and objective microcontexts of adolescent smoking and how they vary by age and gender, 2) to describe adolescents' patterns of acceleration and deceleration in the frequency, intensity and regularity of smoking, and 3) to determine which micro- and macro-level factors differentiate youth who eventually either escalate, maintain, or discontinue their smoking. The research design follows youths ranging widely in their smoking behavior (from recent tryers to weekend smokers), cross-sectioned by grade (8th- 10th), at semi-annual intervals for a period of 18 months. During each data collection period adolescents will provide 1) intensive naturalistic self-reports on their daily experience and smoking behavior for one week and 2) retrospective questionnaire and interview data. Employing hand-held computer self-monitoring devices, we will use a combination of random time-sampling and event sampling while adolescents go about their daily lives to capture both smoking episodes and comparison events. This ecologically valid yet systematically collected data, Capturing thousands of moments nested in 240 adolescents, can provide a heretofore unseen picture of the subjective experience of adolescent smokers and examine its relationship to changes in smoking patterns. Findings from this study have potential for informing both smoking cessation and preventive interventions for adolescents.